yoink

// Play Yoink, an onchain capture-the-flag game on Base. Yoink the flag from the current holder, check game stats and leaderboards, view player scores, and compete for the trophy. Uses Bankr for transaction execution.

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updated:March 4, 2026

SKILL.mdreadonly

SKILL.md Frontmatter

nameyoink

descriptionPlay Yoink, an onchain capture-the-flag game on Base. Yoink the flag from the current holder, check game stats and leaderboards, view player scores, and compete for the trophy. Uses Bankr for transaction execution.

metadata[object Object]

Yoink

Play Yoink, an onchain capture-the-flag game on Base. Yoink the flag from the current holder to start your clock. The player with the most total yoinks holds the trophy.

Contract: 0x4bBFD120d9f352A0BEd7a014bd67913a2007a878 on Base (chain ID 8453)

Game Rules

Yoink the flag - Call yoink() to take the flag from the current holder
Cooldown - You must wait 10 minutes (600 seconds) between yoinks
No self-yoink - You cannot yoink from yourself
Accumulate time - While you hold the flag, your time score increases
Compete for trophy - The player with the most total yoinks holds the trophy (token ID 2)
Track yoinks - Your total yoink count is tracked separately from time

Contract Interface

RPC template:

curl -s -X POST https://mainnet.base.org -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","method":"eth_call","params":[{"to":"0x4bBFD120d9f352A0BEd7a014bd67913a2007a878","data":"SELECTOR+PARAMS"},"latest"],"id":1}' | jq -r '.result'

Function	Selector	Params	Returns
`yoink()`	`0x9846cd9e`	-	(write)
`lastYoinkedBy()`	`0xd4dbf9f4`	-	address
`lastYoinkedAt()`	`0x6a99616f`	-	uint256 timestamp
`totalYoinks()`	`0xa5d0dadd`	-	uint256
`topYoinker()`	`0x6a974e6e`	-	address (trophy holder)
`mostYoinks()`	`0xd2d7774a`	-	uint256 (record)
`COOLDOWN()`	`0xa2724a4d`	-	uint256 (600)
`score(address)`	`0x776f3843`	addr (32B padded)	(yoinks, time, lastYoinkedAt)
`balanceOf(address,uint256)`	`0x00fdd58e`	addr + tokenId	uint256 (FLAG_ID=1, TROPHY_ID=2)

Encoding: Addresses are zero-padded to 32 bytes. score() returns 96 bytes (3 × uint256).

Yoinking

Use Bankr's arbitrary transaction feature:

{
  "to": "0x4bBFD120d9f352A0BEd7a014bd67913a2007a878",
  "data": "0x9846cd9e",
  "value": "0",
  "chainId": 8453
}

Errors

Error	Selector	Meaning
`SlowDown(uint256)`	`0x58d6f4c6`	Cooldown not elapsed. Param = seconds remaining.
`Unauthorized()`	`0x82b42900`	You already hold the flag.

Cooldown check: current_time - lastYoinkedAt() >= 600

Workflow

Query lastYoinkedBy() and lastYoinkedAt() to check status/cooldown
Ensure cooldown elapsed (600s) and you're not current holder
Submit yoink transaction via Bankr
Verify with lastYoinkedBy() or score(address)

Resources

Basescan: https://basescan.org/address/0x4bBFD120d9f352A0BEd7a014bd67913a2007a878 (ABI, events, source)
Source Code: https://github.com/horsefacts/yoink-contracts